10. Charles Ergen is worth $16.9 billion.
Change from last year: +$4.4 billion
Age: 61
Charles Ergen is the founder and chairman of the DISH Network. His company had humble beginnings — in 1980, he, his wife, and a friend started selling satellite dishes out of the back of a truck.
Ergen is notorious for being a frugal leader and micromanager. Up until about 10 years ago, he insisted on signing every check that came out of Dish.
Source: Forbes
9. Paul Allen is worth $17 billion.
Change from last year: +$1.2 billion
Age: 61
Paul Allen cofounded Microsoft with Bill Gates in 1975. He left the company 8 years later after being diagnosed with Hodgkin's Disease.
Since then, he's beat cancer twice and has chosen to live a life of luxury, complete with with megayachts, rock bands, and vintage fighter planes.
Source: Forbes
8. Michael Dell is worth $17.5 billion.
Change from last year: +$1.6 billion
Age: 49
Michael Dell created Dell Computer Corp. from his University of Texas dorm room in 1983.
In October 2013, he won a long, difficult battle to make Dell private again. He says the company has been thriving ever since.
Source: Forbes
7. Steve Ballmer is worth $22.3 billion.
Change from last year: +$4.3 billion
Age: 58
Steve Ballmer stepped down from his position as CEO of Microsoft in February of 2014. He had held the post for 14 years.
Just a few months later, he purchased the Los Angeles Clippers in a record-breaking $2-billion deal.
Source: Forbes
6. Jeff Bezos is worth $29.8 billion.
Change from last year: +$2.6 billion
Age: 50
Jeff Bezos is the CEO and founder of e-commerce giant Amazon.
In April, Amazon introduced a TV set-top box system called Fire TV, and in June Bezos premiered the company's first smartphone. Though reactions to the Fire Phone have not been enthusiastic, Amazon's revenues continue to grow.
Source: Forbes
5. Sergey Brin is worth $31 billion.
Change from last year: +$6.6 billion
Age: 41
Sergey Brin founded Google with Larry Page while the two were ph.D. students at Stanford.
Now he heads up special projects with Google X, the secretive division responsible for risky projects like smart contact lenses, self-driving cars, and Google Glass.
Source: Forbes
4. Larry Page is worth $31.8 billion.
Change from last year: +$6.6 billion
Age: 41
Larry Page founded Google with Sergey Brin.
Three years after Page took over CEO duties, the company's stock has soared. He's overseen a number of key acquisitions this year, including Nest, Twitch, and Dropcam.
Source: Forbes
3. Mark Zuckerberg is worth $34.8 billion.
Change from last year: +$15 billion
Age: 30
Mark Zuckerberg founded Facebook in his Harvard dorm room in 2004.
Zuckerberg's net worth grew by $15 billion this year, the biggest gain of anyone on Forbes' list. In the last year, Zuckerberg led big acquisitions of startups WhatsApp and Oculus VR, and Facebook stock has soared.
He's also caused some controversy in his San Francisco neighborhood, where extensive construction work on his home has made parking difficult for his neighbors.
Source: Forbes
2. Larry Ellison is worth $48.2 billion.
Change from last year: +$9 billion
Age: 70
Earlier this month, Ellison stepped down from his role as the CEO of Oracle, the company he cofounded in 1977. He'll stay on as the company's CTO.
Ellison is known for his cars, yachts, and flashy lifestyle, and he also owns a 97% stake in the Hawaiian island of Lanai.
Source: Forbes
1. Bill Gates is worth $81 billion.
Chane from last year: +$9 billion
Age: 58
Bill Gates cofounded Microsoft with Paul Allen in the late 1970s.
He saw his wealth grow by $9 billion in the last year, thanks in part to a sharp rise in Microsoft shares. He also made an estimated $6 billion in the last 6 months through Cascade, a private investment company that doesn't report its earnings.
Gates is also the wealthiest American across all industries.
Source: Forbes